This document summarizes OpenStack, an open source IaaS project managed by the OpenStack Foundation. It discusses OpenStack's architecture, components, releases, and guest provisioning challenges. OpenStack has a distributed architecture with RESTful APIs and AMQP queues. Its components include Compute, Object Storage, Block Storage, Image Service, Networking, Dashboard, Identity, and Metering. Guest provisioning is tricky as OpenStack components don't handle what happens after a VM boots. Cloudbase-Init was created to standardize guest initialization across operating systems like Linux, Windows, and FreeBSD. It uses various Python libraries and APIs to integrate with different OSes.

1. Interoperable OpenStack guest
provisioning
Alessandro Pilotti
CEO
@cloudbaseit

2. OpenStack
An open source IaaS project
– Apache 2 license
Managed by the OpenStack Foundation
– More than 150 companies joined it including:
– AMD, Intel, Canonical, SUSE Linux, Red Hat,
Cisco, Dell, HP, IBM, NEC, Vmware
Portable
– Mostly used on Linux
Written in Python

3. Releases
Very aggressive schedule
–
•
Essex
–
–
•
Apr 2013
Havana
–
•
October 2012
Cloudbase Solutions involvement - Hyper-V re-included 
Grizzly
–
•
Apr 2012
Hyper-V removed
Folsom
–
–
•
Twice a year
October 2013
Icehouse
–
Apr 2014

4. OpenStack Architecture
• Distributed Components
– Can be deployed on a single server or multiple servers
• Public RESTful API
– Bindings available for various languages (including .Net)
• Queues (AMQP) for private APIs
– Great scalability
• Relational DBs for storing the configuration
– MySQL, PostgreSQL, SQLite (and SQL server)
• UI
– CLI tools
– Web dashboard

5. Components
Compute (Nova)
Object Storage (Swift)
Block Storage (Cinder)
Image Service (Glance)
Networking (Neutron)
Dashboard (Horizon)
Identity (Keystone)
Metering (Ceilometer)
Orchestration (Heat)

6. Architecture 1

7. Architecture 2

8. Component interaction
• AMQP
– RabbitMQ
– Apache Qpid
• API
– RESTful services
• Database
– Any Python SQLAlchemy provider
– Mostly MySQL
– SQL Server required various bug fixes

9. And now the guests
• Nova’s IaaS role ends in the moment in
which the VM boots.
• What happens afterwards, is something that
the guest OS has to sort out.
• Clouds need to support a variety of guest
operating systems:
–
–
–
–
Linux (Ubuntu, RHEL / CentOS and lots more)
Windows Server (and workstation for VDI)
FreeBSD
etc

10. Guest init actions
•
•
•
•
Setting the host name
Manage users / groups
Configure network
Deploy ssh keys for public key auth
– Passwords are BAD!
• Extend partitions automatically
• Run custom scripts
• (and more)

11. Config data?
• Passing configuration data to the guest is
tricky
– Remember: no networking yet!
• The “classic” EC2 approach
– A url on a magic IP http://169.254.169.254
– Various HTTP metadata format exists
• e.g. EC2, OpenStack (Nova)
• An ISO image (ConfigDrive)
– File system reflects the content available via
HTTP

12. Multi platform support
• This is the really tricky part
• IaaS components (e.g. Nova) don’t care
about the guest OS
• Doing provisioning in Linux differs from
Windows and from FreeBSD
• cloud-init works on Linux
– Too tightly coupled with the OS
– Porting is very though
• So we had to start a new project 

13. Cloudbase-Init
• Standard de facto on Windows OpenStack
deployments
• Ported to FreeBSD as well:
– https://github.com/pellaeon/bsd-cloudinit
• “Made in TM”, like the rest of the Cloudbase
stuff 
• 100% Python code

14. Architecture
• Needs to be completely decoupled from the
OS
– Must be portable to any OS
• Highly extensible model
• Basic UML class diagram:
– https://drive.draw.io/#G0B6gjkOr4OobDQnVHY0
QyQ2pSVlE

15. Tricky Windows parts
• CPython works great on Windows
– Lots of modules for basic OS integration
• What to do when we need to go “deeper”?
– PyWin32
• COM
• Wraps lots of Win32 APIs
– PythonNet
• .Net
• Not to be confused with IronPython!
– WMI
• CIM implementation
– Ctypes
•
•
•
•
Direct Win32 calls
Very flexible
Can be tedious to code
Similar to .Net PInvoke

16. Examples -WMI
• Win32_NetworkAdapter
– https://github.com/cloudbase/cloudbaseinit/blob/master/cloudbaseinit/osutils/windows.py
#L340

17. Examples - ctypes
• Win32 - VerifyVersionInfoW
– https://github.com/cloudbase/cloudbaseinit/blob/master/cloudbaseinit/osutils/windows.py
#L557
• Portable - openssl API
– https://github.com/cloudbase/cloudbaseinit/blob/master/cloudbaseinit/utils/crypt.py#L124

18. Examples COM
• COM exposes properties and methods via
getattr / setattr
• Volumes management
– https://github.com/cloudbase/cloudbaseinit/blob/master/cloudbaseinit/plugins/windows/v
ds.py#L322
– https://github.com/cloudbase/cloudbaseinit/blob/master/cloudbaseinit/plugins/windows/e
xtendvolumes.py#L161

19. Logging to serial port
• Fact: serial ports never grow old 
• Clouds use often serial ports to
communicate between hypervisors and
guests
– E.g. OpenStack with KVM
• Linux can easily use serial ports for console
I/O
– That’s how Unix was used in the old days 

20. pyserial
• Windows does not log to serial port
• Serial port can be integrated into Python’s
logging
– https://github.com/cloudbase/cloudbaseinit/blob/master/cloudbaseinit/utils/log.py#L34
• By adding this Log Handler, anytime you
issue a LOG.info/warn/error etc it will be
logged to serial port and collected by KVM
(for example)

21. Q&A